1. Field of the Invention
The present invention relates to an ultraviolet (UV) light-blocking material, and more particularly, to a UV light-blocking composition comprising metal nanoparticles. Exemplary embodiments of the present invention relate to an image display apparatus including the UV light-blocking composition, which can comprise a metal nanoparticle that absorbs and blocks a UV light; and, a dielectric, thereby effectively blocking UV light and demonstrating increased visibility when applied to an image display apparatus such as a mobile phone, and the like.
2. Description of Related Art
Technological improvements are constantly desired in order to improve the system performance of various image display apparatuses such as, for example, mobile phones, including a Digital Multimedia Broadcasting (DMB) phones, and the like, personal computers (PC), wireless broadband Internet (WiBro) terminals, superhigh speed data communication terminals, telematics terminals, digital versatile disc (DVD) portable players, navigation systems, and the like.
One area requiring technological improvement relates to the color intended to originally show in an image display apparatus. Frequently this color cannot be accurately embodied. For example, UV light is frequently leaked out of the light source of a UV light-emitting device in an image display apparatus using the UV light-emitting device, and the like, are generated. In particular, the phenomenon may be significantly increased in an image display apparatus using a plurality of light-emitting devices. The color being intended to show when applying the light source of each light-emitting device, is not accurately embodied, as the color is transmuted due to the influence of the light source from light-emitting devices that are different from each other or, due to the interference of material in a light filter layer used for optimizing each light-emitting device.
In a sensor field, a biomolecule combination affinity or the content of a detected material is measured using surface plasmon resonance (SPR). Herein, surface plasmon is a light-electromagnetic (EM) effect shown in a metal such as gold, and the like wherein a resonance phenomenon is generated in which most light energy is transited to a free electron when light of a specific wavelength is irradiated on the metal. The phenomenon, which is generated when a surface wave is formed as a result, is referred to as “SPR”. In this instance, incident light is not changed into reflected light, and is instead transmitted along a surface. Since the resonance wavelength is shifted depending on a quantitative change in the material composition at a sample surface united with the metal, the phenomenon can be advantageously used in a biosensor. For example, a sensor uses the principle that as a biomolecule combination formed on the surface increases, there is an increase in the wavelength to larger lengths (shorter frequencies), and a quantitative result can consequently be obtained.
The wavelength transition generated is dependent on the metal type, the size of a metal particle, whether the metal is coated, and the dielectric constant of the coating material in a surface plasmon-absorbing wavelength. The location of a surface plasmon-absorbing peak can be predicted by a well-known Mie resonance condition shown in Equation 1 below.∈1(ωs)+2∈m(ωs)=0  [Equation 1]
In Equation 1, ∈1 is a dielectric constant of a metal particle, ∈m is a dielectric constant of a surrounding dielectric, and ωs is a frequency of SPR.
For example, silver, gold, and copper respectively absorb surface plasmons at about 400 nm, about 530 nm, and about 570 nm. Thus, the smaller the size a metal particle is, the shorter the wavelengths that are transmitted. Also, when gold is coated with silicon dioxide (SiO2), a wavelength is transited from about 510 nm to about 540 nm, and when gold is coated with titanium dioxide (TiO2), a wavelength is transited to about 640 nm, since the dielectric constant of TiO2 is higher than the dielectric constant of SiO2 (Minyung Lee et al, “Third-order optical nonlinearities of sol-gel-processed Au—SiO2 thin films in the surface plasmon absorption region”, J. of Non-Crystalline Solids 211(1997), 143-149). Further, a wavelength can be transited at less than about 425 nm when silver is coated with SiO2.
However, SPR technology is currently limited within the sensor field, or it is localized. Also, SPR technology is not used for the purpose of absorbing and blocking a specific wave in an image display apparatus.
Thus, there is therefore a need to develop a technology that uses the SPR of a metal particle as a UV light wavelength-absorbing material in order to improve the visibility of an image display apparatus, and the like.